리눅스 커널의 include/asm-i386/atomic.h의 주요 함수를 Visual C++에서 컴파일 할 수 있도록 만들어 보았습니다.
Atomic 함수는 멀티 쓰레드, 멀티 프로세서 환경에서도 안전하게 변수의 값을 연산할 수 있도록 해주는 함수입니다. 이런 기능을 Atomic 연산이라고 합니다.
리눅스 및 유닉스 계열에서는 Atomic 함수라고 하고, 윈도우에서는 Interlocked 함수라고 합니다.
#ifndef __ARCH_I386_ATOMIC__
#define __ARCH_I386_ATOMIC__
#include <linux/compiler.h>
#include <asm/processor.h>
/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc..
*/
/*
* Make sure gcc doesn't try to be clever and move things around
* on us. We need to use _exactly_ the address the user gave us,
* not some alias that contains the same information.
*/
typedef struct { int counter; } atomic_t;
#define ATOMIC_INIT(i) (i)
/**
* atomic_read - read atomic variable
* @v: pointer of type atomic_t
*
* Atomically reads the value of @v.
*/
#define atomic_read(v) ((v)->counter)
/**
* atomic_set - set atomic variable
* @v: pointer of type atomic_t
* @i: required value
*
* Atomically sets the value of @v to @i.
*/
#define atomic_set(v,i) (((v)->counter) = (i))
/**
* atomic_add - add integer to atomic variable
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v.
*/
static __inline__ void atomic_add(int i, atomic_t *v)
{
__asm
{
mov eax, v
mov ecx, i
lock add dword ptr [eax], ecx
}
}
/**
* atomic_sub - subtract the atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v.
*/
static __inline__ void atomic_sub(int i, atomic_t *v)
{
__asm
{
mov eax, v
mov ecx, i
lock sub dword ptr [eax], ecx
}
}
/**
* atomic_sub_and_test - subtract value from variable and test result
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v and returns
* true if the result is zero, or false for all
* other cases.
*/
static __inline__ int atomic_sub_and_test(int i, atomic_t *v)
{
unsigned char c;
__asm
{
mov eax, v
mov ecx, i
lock sub dword ptr [eax], ecx
sete c
}
return c;
}
/**
* atomic_inc - increment atomic variable
* @v: pointer of type atomic_t
*
* Atomically increments @v by 1.
*/
static __inline__ void atomic_inc(atomic_t *v)
{
__asm
{
mov eax, v
lock inc dword ptr [eax]
}
}
/**
* atomic_dec - decrement atomic variable
* @v: pointer of type atomic_t
*
* Atomically decrements @v by 1.
*/
static __inline__ void atomic_dec(atomic_t *v)
{
__asm
{
mov eax, v
lock dec dword ptr [eax]
}
}
/**
* atomic_dec_and_test - decrement and test
* @v: pointer of type atomic_t
*
* Atomically decrements @v by 1 and
* returns true if the result is 0, or false for all other
* cases.
*/
static __inline__ int atomic_dec_and_test(atomic_t *v)
{
unsigned char c;
__asm
{
mov eax, v
lock dec dword ptr [eax]
sete c
}
return c != 0;
}
/**
* atomic_inc_and_test - increment and test
* @v: pointer of type atomic_t
*
* Atomically increments @v by 1
* and returns true if the result is zero, or false for all
* other cases.
*/
static __inline__ int atomic_inc_and_test(atomic_t *v)
{
unsigned char c;
__asm
{
mov eax, v
lock inc dword ptr [eax]
sete c
}
return c != 0;
}
/**
* atomic_add_negative - add and test if negative
* @v: pointer of type atomic_t
* @i: integer value to add
*
* Atomically adds @i to @v and returns true
* if the result is negative, or false when
* result is greater than or equal to zero.
*/
static __inline__ int atomic_add_negative(int i, atomic_t *v)
{
unsigned char c;
__asm
{
mov eax, v
mov ecx, i
lock add dword ptr [eax], ecx
sets c
}
return c;
}
/**
* atomic_add_return - add and return
* @v: pointer of type atomic_t
* @i: integer value to add
*
* Atomically adds @i to @v and returns @i + @v
*/
static __inline__ int atomic_add_return(int i, atomic_t *v)
{
int __i;
#ifdef CONFIG_M386
unsigned long flags;
if(unlikely(boot_cpu_data.x86==3))
goto no_xadd;
#endif
/* Modern 486+ processor */
__i = i;
__asm
{
mov eax, v
mov ecx, i
lock xadd dword ptr [eax], ecx
mov i, ecx
}
return i + __i;
#ifdef CONFIG_M386
no_xadd: /* Legacy 386 processor */
local_irq_save(flags);
__i = atomic_read(v);
atomic_set(v, i + __i);
local_irq_restore(flags);
return i + __i;
#endif
}
static __inline__ int atomic_sub_return(int i, atomic_t *v)
{
return atomic_add_return(-i,v);
}
#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
/**
* atomic_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, so long as @v was not already @u.
* Returns non-zero if @v was not @u, and zero otherwise.
*/
#define atomic_add_unless(v, a, u) \
({ \
int c, old; \
c = atomic_read(v); \
for (;;) { \
if (unlikely(c == (u))) \
break; \
old = atomic_cmpxchg((v), c, c + (a)); \
if (likely(old == c)) \
break; \
c = old; \
} \
c != (u); \
})
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
#define atomic_inc_return(v) (atomic_add_return(1,v))
#define atomic_dec_return(v) (atomic_sub_return(1,v))
/* Atomic operations are already serializing on x86 */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()
#define smp_mb__before_atomic_inc() barrier()
#define smp_mb__after_atomic_inc() barrier()
#include <asm-generic/atomic.h>
#endif
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